Frederick Post slide rules marked 1444 and 1452 (with "V" date codes)
This rules are mis-marked models 1444K and 1452W.

No model "1444" or "1452" was listed in Post Catalogs in the early 1970s but a fair number of specimens with those model numbers and date codes around 1971 exist.  Here's a hypothesis of why:  About 1971 Post decided to drop the "K" from model 1444K and the "W" from model 1452W.  After ordering rules with the new model numbers, Post decided to stick with the old 1444K and 1452W model numbers.  Consequently, many boxes marked "1444K" and "1452W" contained rules marked "1444" and "1452."

Top: Marked "1444."  Date code "VC" (March 1971)
Bottom: Marked "1452."  Date code "VJ"  (October 1971)